Drive trains consisting of components, for example transmissions, clutches and connecting elements (shafts), are important parts, inter alia, of different electrical energy generation plants, for example wind energy plants, hydroelectric plants etc.
The drive train performs the task of establishing a mechanical connection between a drive (for example a rotor of a wind energy plant) and an output (for example a corresponding generator), via which connection energy is transmitted by means of a rotational movement. Drive train components such as transmissions are used to translate the rotational speed and the torque present at the drive into values which correspond to the operating range of the output. If necessary, clutches are used for separation between the drive and the output and shafts establish the mechanical connection between the components involved. Further components, such as mechanical brakes or the like, may also be integrated in the drive train.
Since the components involved and also the connection of the components are not arbitrarily rigid but rather have a finite stiffness, a movement of the shafts results. The movement of the shafts has a disadvantageous effect on the measurement accuracy.
Even though the present disclosure is primarily described within the scope of this application with respect to wind energy plants, it is not restricted in any way to wind energy plants or devices for generating energy but rather can be used, in principle, in all apparatuses in which torsional vibrations of shafts, axles and the like, in particular also of shafts and axles with interposed transmissions, may arise.
DE 10 2011 118 831 A1 thus describes a method and a measuring system which use angle differences of shafts to calculate a torque which can be used as an input variable for a controller which can be used to damp vibrations in the drive train.
A similar approach is followed in US 2008/0067815, according to which a signal is generated from changes in the generator rotational speed, which signal is used to achieve damping via the generator actuating torque.
The disadvantage of all these solutions can be considered to be the fact that the signal quality for the rotational speed, torque and torsional angle can be determined only with limited accuracy on account of the movement of the shafts with respect to the holder.
It is therefore desirable to specify a possible way of detecting a rotational speed, a torque and/or a torsional angle in drive trains with high accuracy.